Indicating mechanism



July 18, A ROTH INDICATING MECHANISM Filed May 12 1927 2 Sheets-Sheet l/0 Y WITLESSES: a7 /4 INVENTOR July l8,' 1933. A. ROTH INDICATINGMECHANISM 2 Sheets-Sheet 2 Filed May 12, 1927 INVENTOR fi/beflEof/iATTORNEY WITNESSES: 5Q Id Patented July 18, 1933 isiaen lies? ALBERTROTH, 0F PITTSBURGH, IENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC &MANUFACTURING COMPANY, A CORPORATION INDICATING Application filed May12,

My invention relates to controlling mechanism, and it h as particularrelation to devices for controlling the adjustment of a plurality ofvariable reactors such as are commonly employed in radio receiving andtransmitting apparatus.

One objectof my invention is to provide a reactor-controlling devicethat iscapable of being quickly and accurately adjusted.

Another object of my invention is to proride a reactor-controllingdevice so interconnected with indicating means that the relariveposition of the said reactor with respect to its entire rangeofvariation is at all times apparent. i v

Another object of my invention is to provide a reactor-controllingdevice that is particularlyadapted to be incorporated into receivingsystems of the type known as superheterodyne. in which condensers of thesocalled "straight-line-frequency variety are preferably employed inorder to maintain a constant frequency difference between certain tunedcircuits.

Still another, and more specific, object of my invention is toprovidemeans forindicating, by rectilinear movement of a pointer withrespect to a fixed index, the angular po sition of the movable portionsof a plurality of variable reactors with respect to the fixedportionsthereof.

it has heretofore been the practice, in connection with the variablereactors incorporated in radio receiving sets, to indicate the settingthereof by the relative position of movable indices carried thereby withrespect to a fixed point on the panel of the set. In my copendinn'application, Serial No. 36,105, filed June 10, 1925 I have illustratedand described apparatus of the type just mentioned, and the presentinvention is tobe considered as an improvement thereon.

In general, it may be said that my invention consists in providinginstrumentalities whereby the rotary motion of'a control device for avariable reactor is translated into proportional rectilinear motion ofan indicator with reference to a stationary index carried bva panel. Ialsoprovide means whereby the stationary index is removably supported orr innsYLvAnIA MECHANISM 1927. Serial No. 190,716.

on the panel,-whereby the said index may be replaced when soiled withoutdisturbing the precalibration of the set.

Among thenovel features of my invention are those particularly set forthin the ap pended claims. The invention in its generic aspect, however,as well as further objects and advantages thereof, will best beunderstood.

by reference to'the following description of certain specificembodiments, taken in con nection with the accompanying drawings, inwhich: i

Figure 1 is a view from above'of a radio set panel supporting aplurality of condensers equipped with a preferred embodiment ofi yinvention, 1

Fig. 2 is a front 'elevatioual-view of a'radio set panel showing therelation of the rec- .tilinearly-movable indicators with respect to thestationary indeX, and

Fig. 8 is a sectional view as seen from the left along'a linecorresponding to the line III-1110f Fig. 2. I

Referring to the drawings, a panel 1. preferably made of an insulatingmaterial such as bakelite, hard rubber, or the like, is provided with alargeopeningv 2' in order to 7 permit the extension therethrongh ofcertain apparatus that will later be specifically de scribed. Anescutcheon plate 3 having aplurality of openings 4, 5,6 and 7therethrough is affixed to the front face of the panel in such manner asto serve as a cover for the panel opening, and is held in positionthereon by a plurality of screws 8 or equivalent devices,

The plate carries a plurality of devices 10 and 11 in the nature oflabel-holders, such as are commonly used on the fronts of drawers offiling cabinets, etc., in which are removably carried stationaryindex-slips 12 and 13 which slips may bepre-calibrated withradio-station call-letters, or itially be left blank.

The plate 3 is also provided with a series 14 of permanent indici aindicating the frequencies'. corresponding to variousv settings .of aplurality of indicating devices 15 and 16 that will later be describedmore in detail.

Minor lateral portions of two adjustingdiscs 17 and 18 project throughthe plate 3,

which may in- 28 and 30, respectively.

Inasmuch as the condensers 24 and 25, and the lClJHStlDg andpositionandicating devices associated therewith, are identical, furtherdescrlption Wlll be confined to the condenser A plurality ofspacer-elements 31 are mounted between the end plates, and extendparallel to the shaft 20 carrying therotor 22. These spacer-elementssupport a plurality'of stator plates 32 that are so arranger as tointerleave with the rotor plates 26 when the shaft 20 is rotated by theadjustingdisc 17.

An elongated'member 33 provided at one end with a guiding-slot 34 isattired to the rear surface to the plate 3 by a screw 35 or otheranalogous devices, and extends perpendieu larly thereto. The member isprovided with an opening through which extends the end of the shaft 20that carries the adjusting disc 17. That portion of the shaft whichextends beyond the member has aifixed thereto a small pinion 36 thatmeshes with a larger pinion 37 rotatably mounted on't-he member 33intermediate the shaft 20 and the plate 3. An arm 38 is permanentlyaffixed to the pinion 37 radially thereof, and is pro vided at its freeend with an opening through which eXtends a pin 40 carried by apointerdevice 41. v V

The pointer-device 41 extends from the rear of the panel through theelongated open ing 4 in the escutcheon plate 3, and carries, on the endprojecting to the front of the panel, the indicating device 15previously referred to. The opposite end of the poi nterdevice 41 isprovided with'a'n opening in .which is riveted a pin 42 arranged toslide in the guiding-slot 34. The pin has an enlarged head, clearlyshown in Fig. 1, that prevents dis-association of the pointer and theelongated member when the device is operated.

The angular position of the small pinion 36 on the shaft 20 is soadjusted with reference to the large pinion 37 that when the condenseris at its mid-capacity setting, the pointer device 41. the arm 38carried by the large pinion 37 and the elongated member 33 are paralleland extend in a direction perpendicular to the plane of the panel 1. iIn this position the transverse indicating device 15 is in the positionshown in Fig. 2.

In order that the operation of my device shall be thoroughly understood,reference should now be made to Fig. 3.

Assume first that the relative position of the various elements is thatshown in the drawing, andthat the adjusting disc 17 is given anincrement of rotation in the direction indicated by the arrow. By reasonof the meshing of pinion 36, carried by the shaftto which the disc 17 isafiixed, with the large pinion 37, the latter pinion is accordinglycaused to rotate in the direction indicated by the arrow thereon, andthe end of the arm 38 consequently moves in an arc in dicated by thedotted line A-B. On account of the rotatable connection, by means of thepin 40, of the arm 38 and the pointerdevice 41, that portion ofthepointer 41 which is immediately associated with the said pin is alsocaused to travel in the dotted arc.

An increment of motion downward of the pin 40 accordingly tends to causethe pointer device to describe an are having the pin 42 as its center.If the said pin 42'were fixed in position 'on the member 33, and the arm38 provided with a slot in which the pin 40 could slide, the indicatingdevice would therefore not move in a rectilinear path with reference tothe panel, but would describe an are having the panel as a chordthereof. Inasmuch, however, as there is no relative sliding motionbetween the arm 38 and the pointer 41, andthe end of the pointer 41carrying the pin'42 is free to move in a direction perpendicular to thepanel, the center of curvature of the arc in which the indieating-device15 tendsto travel is constantly movin further awa "from the panel. The.

motionof the pin 42 is approximately proportional to the cosine of theangle through whichthe arm 38 turns, and the relative dimensions of thevarious parts are so chosen that such motion is suflicient to compensatethe curvature of the arc in'which the indicating device tends to travel,with the con sequence that the path of the said indicatingdevice 15 issubstantially rectilinear and parallel to the index-strip.

' Fig. 3 is drawn to scale from an actual embodiment of my invention,and the relative dimensions thereof, if followed, will give rise to' anoperative structure. v

It is also, of course feasible to adapt my invention to the control ofcondensers of either the straight-line wave-length or straight-linecapacity types, no changes beingnecessary in the mechanism.

I have particularly pointed out the use of my invention in connectionwith condensers of the straight-line frequency type, inasmuch as suchcondensers are of extreme importance in receiving systems of thesuper-heterodyne type. In such systems, it is necessary that a constantfrequency-difference be maintained between the frequencyof a localoscillator and the frequency to which the input circuit of the system istuned, this constant frequency-diiference being that frequency to whichthe intermediate amplifier is tuned.

If, therefore, one of the adjusting discs controls the radio frequencyinput tuning of a super-heterodyne system, the other disc may bearranged to control the tuning of the local oscillator, and the severalinductors associated with the condensers may be so adjusted that whenthe indicating members and 16 are opposite at any point in their travel,the same frequency difference exists between the tuning of the severalcircuits as previously described.

Inasmuch as the travel of the indicating devices along the stationaryindices may be arranged to have a straight line relation to Y thefrequency of the circuit or circuits associated therewith, it isaccordingly apparent that I have provided avery simple and easilyoperated device for indicating the tuning of either a superheterodynereceiving system or a receiving system in which are incorporated aplurality of tuned stages.

The index holding devices 10 and 11, into which may be inserted eitherblank strips of roughened celluloid or cardboard on which the variousstation call letters may be written as desired, prove to be a decidedconvenience, inasmuch as the strips may be removed when soiled and maybe replaced by similarly marked strips in the full assurance that thepre-calibration of the set will not be changed.

Another very decided advantage of my invention lies in the fact that thesettings for all of the stations within range of the set equippedtherewith are visible at a glance. In tuning systems of most of theusual types,

the major portions of the drums carrying the station-call letters arehidden behind a panel and, consequently, the tuning of the set cannot bequickly and easily changed from one extremeposition to the other. l/Vhenall of thecall letters are in plain view, it is obvious that the processof tuning is greatly simplified. v

In addition to the label holders and removable strips, the indexindicating in kilo-cycles the frequencies which correspond to any adjustment of the tuning device is an additional advantage, inasmuch astation broadcasting on a known frequency, or wave length, may beexpeditiously tuned by adjusting the indicating device to correspond tosuch frequency. a 7

Although I have shown and described only a single specific embodiment ofmy invention, it is not to be restrictedvthereto, since modificationsthereof are possible. My invention, therefore, is only to be limited by.the prior art and by the spirit of the appended claim.

I claim as my invention:

In combination, a panel having a plurality of openings extendingtherethrough, a shaft lying parallel to one face of said panel and;

in spacedrelationship thereto, an adjusting disc-llke control elementaflixed to said shaft at right angles to said panel and partiallyextending through one ofsaid openings, an

index-device mounted on the other face of said panel adjacent theprojecting portion of said control element, an indicating device, andmeans interconnecting said disc-like control element and said indicatingdevice whereby the latter is constrained to move in a rec-v tilinearpath substantially parallel and adjacent to said index-device uponmovement of said control element.

ALBERT BO H.

